When specifying system requirements, we want a language that can express the requirements in the simplest and most intuitive form. An expressive and intuitive language makes specifying requirements easier and less error-prone. Although our MaC system provides an expressive language, called MEDL, to specify safety requirements, it is generally awkward to express an order of events with complex timing dependencies, timing constraints, and frequencies of events. MEDL-RE extends our MEDL language to include regular expression and three associated events to easily specify timing dependencies and its timing constraints. Our regular expression is unique in a way that a user can specify which events are relevant to a regular expression. This feature makes it easy when a user wants to specify a requirement of one specific component of a system.